Fig 2. A gene expression block.

A GRN that consists of gene expression blocks. A block consists of a gene reactions block and a protein reactions block. The gene reactions are described in the text. TF is a vector of TFs which can be monomers, dimers, or higher order multimers. Dⁱ is a vector whose components consist of the ${\text{D}}_j^i$’s. The dimension of TF is equal to the number of binding sites of the gene.